Conventional traffic light signaling at intersections only works well under good weather conditions. When sunglare or heavy precipitation are present, it can be difficult to understand whether a given traffic signal glows red, green or amber. Often under such conditions a driver will finally identify the traffic signal later than he or she should, with little time left to stop the vehicle when the signal glows red. During twilight periods, when eyes have difficulty distinguishing objects in the partially illuminated landscape, it can be just as difficult to understand when an intersection is being approached, and to watch for the presence of a traffic signal. In addition to these problems which affect all drivers, a significant number of drivers have red green color blindness which may impair their ability to distinguish between the conventional green light signal for “GO” and the conventional red light signal for “STOP”. Thus, under poor lighting or poor weather conditions, a driver may fail to stop before an intersection when the traffic signal glows red and thereby endanger himself and others.
Besides traffic signals, the driver must continually monitor other visual information. Even under the worst weather conditions, e.g. snowstorms, duststorms, fog, etc., the driver must understand the position of the vehicle in relation to the road and other vehicles. If the driver fails to understand the edge of the road and the vehicle veers off the road, a serious collision may result. At minimum, the driver may not be able to return the vehicle to the road. In such weather, when vehicles ahead of the driver slow down, a delay in perceiving such condition could lead to a serious collision.
Much needed driver information presumes keen and watchful perception on the part of the driver. The driver has must watch for and perceive visual events that appear with only a moment's notice. Road hazards, such as potholes and debris, pose serious risks to vehicles. Animals in the roadway, whether still or live, cause damage to vehicles and may cause vehicles to veer off the road. Caution and warning signs must also be perceived in time to be heeded. If vehicles approach a sharp turn or lane merge too fast, they may collide or veer off the road.
For all these reasons, an on-board vehicle signaling system is needed which complements external visual driver information by receiving and indicating driving-related signals such as the phase of a traffic stoplight being approached by the vehicle.